Because of the rapid development of heavy industry, air pollution has become the most dangerous enemy to modern human beings. The smoke from the chimney of factories is now threatening the survival of agriculture, animals, and human beings. Moreover, smoke from chimneys often contains poisonous gas which can cause death to thousands of people such as in the tragedy that took place in India in 1984. It is therefore fundamental that all factories be equipped with smoke treatment apparatus, especially those factories engaged in the manufacture of pulp and paper, dye materials, poisonous chemicals, and woven textiles.